Occupied Jerusalem: Israeli Defence Minister Ehud Barak on Wednesday rebuffed a call by UN Secretary-General Ban Ki-moon to allow humanitarian aid into the Gaza Strip through border posts Israel has largely sealed in two weeks of violence.

Asked by Israeli Army Radio about Ban's appeal and whether Israel intends to reopen the passages, Barak said: "No. There needs to be calm in order for the crossings to be opened."

Ban telephoned outgoing Israeli Prime Minister Ehud Olmert on Tuesday and "strongly urged (him) to facilitate the freer movement of urgently needed humanitarian supplies" and UN aid workers into the Gaza Strip, the UN press office said.

Israel closed the crossings after Palestinian fighters responded with daily rocket salvoes to an Israeli army incursion on November 4 into the Hamas-run territory, where a five-month-old, Egyptian-brokered ceasefire had largely been holding.

Barak acknowledged in the radio interview that the violence was touched off by the Israeli raid, which the army said destroyed a tunnel at the frontier that Gaza fighters dug and could have been used to try to seize Israeli soldiers.

More than a dozen Palestinian fighters have been killed in in the past two weeks. Several Israelis have been slightly wounded by dozens of rockets.

The United Nations and humanitarian agencies have voiced concern that Israel's blockade of the Gaza Strip, where about half of the population of 1.5 million is dependent on UN aid, could soon spiral into a humanitarian crisis.

"Israel is sensitive and attentive to the humanitarian needs. But also, Hamas has to impose the ceasefire on smaller groups and this will help it receive more goods through the crossings [borders]," Barak said.

"Should the other side choose to go back to the ceasefire, there will be a ceasefire," Barak said. "And if they choose to escalate there will be an operation. We are not scared of an operation but neither are we eager for it."

Olmert said on Sunday he commissioned a new plan for military action in the Gaza Strip to curb rocket attacks.